As one of lighting devices, there is known an organic electroluminescent lighting device that includes an organic light emitting film as a light source. In the organic electroluminescent lighting device, the organic light emitting film is sandwiched between a transparent anode film and a cathode film, and emits light when an electric field is generated between the electrodes. The light is transmitted through the anode film to be applied to the outside. For the anode film, a transparent conductive material (or transparent metal oxide) such as ITO (Indium Tin Oxide), ZnO, SnO 2 (Nesa glass) is used. The transparent conductive material (or transparent metal oxide) has relatively large electrical resistivity ρ(Ω·m). Power is generally supplied to the anode film from both of its ends. Accordingly, wring resistance is larger farther from both ends. Since the increase of the wiring resistance is accompanied by the increase of a voltage drop, the voltage is no longer applied uniformly to the entire organic light emitting film. The luminance of the organic light emitting film depends on the voltage. Thus, when the voltage is not applied uniformly to the organic light emitting film, there is a possibility that the luminance of the organic light emitting film will be nonuniform. To reduce the wiring resistance, therefore, there is known a technology of forming auxiliary electrode films whose resistance is lower than the anode film in a lattice shape on the surface of the anode film (JP2004-14128A).
FIG. 1A is a top view showing organic electroluminescent lighting device 100 according to the present invention. FIG. 1B is a sectional view cut along the line A-A shown in FIG. 1A. FIG. 1C is a sectional view cut along the line B-B shown in FIG. 1A. FIG. 1A shows the seen-through state of the inside of organic electroluminescent lighting device 100. FIGS. 1B and 1C show the separated state of organic light emitting film 114 and electrode film 115 from organic electroluminescent lighting device 100. FIGS. 2A to 2E are top views each showing the manufacturing process of organic electroluminescent lighting device 100 shown in FIG. 1A.
To manufacture organic electroluminescent lighting device 100 shown in FIG. 1A, first, a sheet of electrode film 111, power supply terminal films 121, and power supply terminal films 131 are formed on the surface of transparent substrate 110 (refer to FIG. 2A). Electrode film 111 and power supply terminal film 121 are integral with each other, and power supply terminal film 131 is separated from electrode film 111 and power supply terminal film 121. For electrode film 111 and power supply terminal films 121 and 131, transparent conductive materials (or transparent metal oxides) (e.g., ITO) are used. Then, auxiliary electrode films 112 are formed in a lattice shape on the surface of electrode film 111 by using metallic materials (e.g., chromium) whose electrical resistivity is lower than electrode film 111 (refer to FIG. 2B). Then, insulating films 113 are formed on the surfaces of auxiliary electrode films 112 (refer to FIG. 2C). Then, organic light emitting film 114 is formed on the surface of electrode film 111 and the surfaces of insulating films 113 (refer to FIG. 2D). Lastly, electrode film 115 is formed on the surface of organic light emitting film 114 and the surfaces of power supply terminal films 131 (refer to FIG. 2E).
In organic electroluminescent lighting device 100 thus configured, when power is supplied between power supply terminal film 121 and power supply terminal film 131 from a power source, organic light emitting film 114 emits light. At this time, since there are auxiliary electrode films 112 formed on the surface of electrode film 111, wiring resistance is reduced. Thus, the value of a dropping voltage is also reduced. As a result, nonuniformity of luminance in the organic light emitting film can be prevented.